U.S. patent number 11,440,375 [Application Number 16/396,833] was granted by the patent office on 2022-09-13 for radiant heater device.
This patent grant is currently assigned to DENSO CORPORATION. The grantee listed for this patent is DENSO CORPORATION. Invention is credited to Kimitake Ishikawa, Hiroyasu Oide, Hideki Seki, Yusuke Tanaka.
United States Patent |
11,440,375 |
Seki , et al. |
September 13, 2022 |
Radiant heater device
Abstract
A radiant heater device for generating a radiant heat, includes
a substrate portion having a plate shape and made of an
electrically insulating material, a surface member having a sheet
shape and disposed on one surface side of the substrate portion,
and a heat generation portion formed on the other surface side of
the substrate portion. The surface member is formed of a fiber
fabric that is provided with a space portion recessed toward the
substrate portion in a thickness direction of the surface member
and that restricts a heat transfer in a surface direction of the
surface member by the space portion.
Inventors: |
Seki; Hideki (Kariya,
JP), Ishikawa; Kimitake (Kariya, JP), Oide;
Hiroyasu (Kariya, JP), Tanaka; Yusuke (Kariya,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya |
N/A |
JP |
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Assignee: |
DENSO CORPORATION (Kariya,
JP)
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Family
ID: |
1000006554917 |
Appl.
No.: |
16/396,833 |
Filed: |
April 29, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190248211 A1 |
Aug 15, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2017/036355 |
Oct 5, 2017 |
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Foreign Application Priority Data
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Nov 16, 2016 [JP] |
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JP2016-223467 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B
3/342 (20130101); H05B 3/267 (20130101); B60H
1/2226 (20190501); F24D 5/08 (20130101); H05B
3/10 (20130101); H05B 3/36 (20130101); B60H
1/2227 (20190501); H05B 3/26 (20130101); H05B
3/20 (20130101); B60H 1/22 (20130101) |
Current International
Class: |
B60H
1/22 (20060101); H05B 3/34 (20060101); H05B
3/36 (20060101); H05B 3/20 (20060101); F24D
5/08 (20060101); H05B 3/10 (20060101); B60H
1/00 (20060101); H05B 3/26 (20060101) |
References Cited
[Referenced By]
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Nov 2008 |
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JP |
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JP |
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JP |
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2013251184 |
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2014-205372 |
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2014189251 |
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Oct 2014 |
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2016113137 |
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Jun 2001 |
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WO |
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WO-2013179836 |
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Dec 2013 |
|
WO |
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Other References
JP 2008-265716 A, Matsushita Electric, Nov. 2008, "Vehicle Heater,"
partial translation. (Year: 2008). cited by examiner.
|
Primary Examiner: Pelham; Joseph M.
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation application of
International Patent Application No. PCT/JP2017/036355 filed on
Oct. 5, 2017, which designated the United States and claims the
benefit of priority from Japanese Patent Application No.
2016-223467 filed on Nov. 16, 2016. The entire disclosures of all
of the above applications are incorporated herein by reference.
Claims
The invention claimed is:
1. A radiant heater device for generating a radiant heat,
comprising: a substrate portion having a plate shape and made of an
electrically insulating material; a surface member having a sheet
shape and disposed on one surface side of the substrate portion;
and a heat generation portion formed on the other surface side of
the substrate portion, wherein the surface member is formed of a
fiber fabric that is provided with a space portion recessed toward
the substrate portion in a thickness direction of the surface
member, the fiber fabric is in contact with the substrate portion,
the fiber fabric has a mesh shape, and the fiber fabric has a
double mesh structure in which two knitted fabrics are superposed
on each other.
2. The radiant heater device according to claim 1, wherein the
fiber fabric is formed of a nonwoven fabric.
3. The radiant heater device according to claim 1, wherein the mesh
shape is a lattice shape.
4. The radiant heater device according to claim 1, wherein the mesh
shape is a honeycomb shape.
5. The radiant heater device according to claim 1, wherein the
fiber fabric is formed by interposing air between a plurality of
fibers.
6. A radiant heater device for generating a radiant heat,
comprising: a substrate portion having a plate shape and made of an
electrically insulating material; a surface member having a sheet
shape and disposed on one surface side of the substrate portion;
and a heat generation portion formed on the other surface side of
the substrate portion, wherein the surface member is formed of a
fiber fabric that is provided with a space portion recessed toward
the substrate portion in a thickness direction of the surface
member, the fiber fabric is in contact with the substrate portion,
and the heat generation portion has a structure to restrict a heat
transfer in a surface direction of the substrate portion.
7. A radiant heater device for generating a radiant heat,
comprising: a substrate portion having a plate shape and made of an
electrically insulating material; a surface member having a sheet
shape and disposed on one surface side of the substrate portion;
and a heat generation portion formed on the other surface side of
the substrate portion, wherein the surface member is formed of a
fiber fabric that is provided with a space portion recessed toward
the substrate portion in a thickness direction of the surface
member, the fiber fabric has a mesh shape, and the fiber fabric has
a double mesh structure in which two knitted fabrics are superposed
on each other.
Description
TECHNICAL FIELD
The present disclosure relates to a radiant heater device.
BACKGROUND
Conventionally, there is a radiant heater device for generating a
radiant heat.
SUMMARY
The present disclosure provides a radiant heater device that
includes a substrate portion having a plate shape and made of an
electrically insulating material, a surface member having a sheet
shape and disposed on one surface side of the substrate portion,
and a heat generation portion formed on the other surface side of
the substrate portion. The surface member is formed of a fiber
fabric that is provided with a space portion recessed toward the
substrate portion in a thickness direction of the surface member
and that restricts a heat transfer in a surface direction of the
surface member by the space portion.
BRIEF DESCRIPTION OF DRAWINGS
The above and other objects, features and advantages of the present
disclosure will become more apparent from the following detailed
description made with reference to the accompanying drawings. In
the drawings:
FIG. 1 is a diagram showing a state in which a radiant heater
device according to a first embodiment is attached to a
vehicle;
FIG. 2 is a plan view of the radiant heater device according to the
first embodiment;
FIG. 3 is a cross-sectional view taken along a line III-III in FIG.
2;
FIG. 4A is an external view of a knitted fabric according to the
first embodiment;
FIG. 4B is a schematic diagram showing a way of heat transfer in a
comparative example;
FIG. 4C is a schematic diagram showing a way of heat transfer
according to the first embodiment;
FIG. 5 is a diagram showing a relationship between a unit weight
(for example, a thickness and a weight) of a surface member and a
contact temperature of a contact portion;
FIG. 6 is a graph showing a relationship of a contact temperature
of the contact portion when a knitted fabric is raised or
flocked;
FIG. 7 is a graph showing characteristics of the contact
temperature of the contact portion according to a difference in
composition of the surface member;
FIG. 8 is a graph showing characteristics of the contact
temperature of the contact portion according to a difference in the
amount of unevenness of the knitted fabric of the surface
member;
FIG. 9 is a graph showing a relationship between the amount of
unevenness relative to a thickness and the contact temperature of
the contact portion when a nonwoven fabric is used as the surface
member;
FIG. 10 is a graph showing characteristics of the contact
temperature of the contact portion according to the difference in
the amount of unevenness of the surface member;
FIG. 11 is a cross-sectional view of a radiant heater device
according to a second embodiment, which corresponds to FIG. 3;
FIG. 12 is an external view of a nonwoven fabric according to the
second embodiment; and
FIG. 13 is an external view of a surface member according to a
third embodiment.
DETAILED DESCRIPTION
Before describing embodiments of the present disclosure, a radiant
heater device according to a comparative example will be described
below. The radiant heater device according to the comparative
example includes a substrate portion providing a surface made of an
electrically insulating material, and multiple heat generation
portions disposed in parallel to each other so as to extend along
the surface of the substrate portion. In the radiant heater device,
a temperature of the heat generation portion rises in response to
energization, and when an object comes into contact with the heat
generation portion, the temperature of the heat radiation portion
falls. The radiant heater device further includes a surface layer
on the surface of the substrate portion, and the surface layer is
configured by a sheet made of a thermoplastic resin and having a
plurality of protrusion portions. Thus, a contact area between an
object and the surface layer is small, and a direct heat transfer
from the heater device to the object is restricted.
Since the radiant heater device according to the comparative
example is formed with the surface layer made of a sheet of resin,
it has been found by studies of the present inventors that it is
insufficient to quickly lower a temperature of a contact portion
when the object comes into contact with the contact portion.
According to one aspect of the present disclosure, a radiant heater
device for generating a radiant heat, includes a substrate portion
having a plate shape and made of an electrically insulating
material, a surface member having a sheet shape and disposed on one
surface side of the substrate portion, and a heat generation
portion formed on the other surface side of the substrate portion.
The surface member is formed of a fiber fabric that is provided
with a space portion recessed toward the substrate portion in a
thickness direction of the surface member and that restricts a heat
transfer in a surface direction of the surface member by the space
portion.
According to such a configuration, since the surface member is
formed of the fiber fabric that is provided with the space portion
recessed toward the substrate portion in the thickness direction of
the surface member and a heat transfer in the surface direction of
the surface member is restricted by the space portion, the
temperature of the contact portion when the object comes into
contact with the surface member can be lowered more quickly.
Hereinafter, a plurality of embodiments will be described with
reference to the drawings. In each of the embodiments, the same
reference numerals are assigned to portions corresponding to the
items described in the preceding embodiments, and a repetitive
description thereof may be omitted. When only a part of the
configuration is described in each form, the other forms described
above can be applied to the other parts of the configuration.
First Embodiment
A radiant heater device 1 according to a first embodiment of the
present disclosure will be described with reference to FIGS. 1 to
10. In FIG. 1, the radiant heater device 1 according to the first
embodiment is installed in an interior of a moving object such as a
road traveling vehicle, a ship, or an aircraft. The radiant heater
device 1 configures a part of a heating device 10 for the interior.
The radiant heater device 1 is an electric heater that is supplied
with a power from a power supply such as a battery or a generator
mounted on the moving object to generate a heat. The radiant heater
device 1 is in the form of a thin plate-shape. The radiant heater
device 1 generates the heat when supplied with power. The radiant
heater device 1 radiates a radiant heat R primarily in a direction
perpendicular to a surface of the radiant heater device 1 in order
to warm a target object positioned in the direction perpendicular
to the surface.
A seat 11 on which an occupant 12 is seated is installed in the
interior. The radiant heater device 1 is installed in the interior
so as to radiate the radiant heat R to feet of the occupant 12. The
radiant heater device 1 can be used as a device for providing
immediate warmth to the occupant 12 immediately after activation of
the heating device 10. The radiant heater device 1 is installed on
a wall surface of an interior. The radiant heater device 1 is
installed so as to face the occupant 12 who is in an assumed normal
posture. For example, the road traveling vehicle has a steering
column 13 for supporting a steering wheel 14. The radiant heater
device 1 can be installed on a lower surface of the steering column
13. The radiant heater device 1 is installed so that a surface of
the radiant heater device 1 is exposed to the interior.
In FIG. 2, the radiant heater device 1 extends along an X-Y plane
defined by an axis X and an axis Y. The radiant heater device 1 is
formed in a thin plate-shape having a substantially rectangular
shape. The radiant heater device 1 includes a substrate portion 2,
multiple electrodes 3 and 4, and multiple heat generation portions
5. In the drawing, the electrodes 4 and the heat generation
portions 5 embedded in the substrate portion 2 are hatched.
FIG. 3 shows a III-III cross section of FIG. 2. In the figure, the
radiant heater device 1 has a thickness in a direction of the axis
Z. The radiant heater device 1 may also be referred to as a planar
heater, which radiates the radiant heat R primarily in a direction
perpendicular to the surface.
The substrate portion 2 is made of a resin material which provides
an excellent electrical insulation property and withstands a high
temperature. The substrate portion 2 is formed in a plate-like
shape. The substrate portion 2 is a multilayer substrate.
The substrate portion 2 has a front surface layer 21 and a back
surface layer 22. Those layers 21 and 22 are provided by sheets of
thermoplastic resin.
A surface member 80, which will be described later, is bonded to
the front surface layer 21. A side of the front surface layer 21 to
which the surface member 80 is bonded corresponds to one surface
side of the substrate portion 2. The surface member 80 is exposed
toward the interior. The surface member 80 provides a front surface
of the radiant heater device 1. The back surface layer 22 provides
a back surface of the radiant heater device 1. An intermediate
layer 23 is disposed between the front surface layer 21 and the
back surface layer 22. Materials forming the electrodes 3 and 4 and
the heat generation portions 5 is supported on one or more of the
layers 21, 22, and 23, A side of one or more of the layers 21, 22,
and 23 on which the heat generation portions 5 are supported
corresponds to the other surface side of the substrate portion 2.
The substrate portion 2 is a member for supporting the electrodes 3
and 4 and the heat generation portions 5.
The material of the substrate portion 2 provides a thermal
conductivity which is sufficiently lower than that of the
electrodes 3 and 4 and the heat generation portions 5. The
substrate portion 2 provides a heat insulating portion for reducing
a heat conduction between two adjacent heat generation portions
5.
The multiple electrodes 3 and 4 include the external electrodes 3
at least partially exposed to the outside of the radiant heater
device 1 and the internal electrodes 4 disposed in the substrate
portion 2. The electrodes 3 each include a pair of electrodes 31
and 32 for supplying an electric power. The pair of electrodes 31
and 32 provide terminals of the radiant heater device 1. The
electrodes 3 are disposed on an outer surface of the substrate
portion 2 including an outer edge portion, the front surface, and
the back surface of the substrate portion 2. A part of the
electrodes 3 is embedded in the substrate portion 2 and
electrically connected to the electrodes 4. The electrodes 4 may be
exposed on an outer surface of the substrate portion 2 and used as
terminals for supplying the electrodes.
The electrodes 4 are embedded in the substrate portion 2. The
electrodes 4 are also busbar portions for distributing the electric
power to the multiple heat generation portions 5 to be described
later. The electrodes 4 extend from the electrodes 3. The
electrodes 4 have an electrical resistance value sufficiently lower
than that of the multiple heat generation portions 5. The electric
resistance value of the electrodes 4 is set so as to be able to
reduce a heat generation in the electrodes 4. The electrodes 4
evenly distribute a current to the multiple heat generation
portions 5. The electrodes 4 have a pair of electrodes 41 and 42
for supplying the electric power. The pair of electrodes 41 and 42
are disposed apart from each other at both ends of a unit region of
the substrate portion 2. The pair of electrodes 41 and 42 extend
along both sides of the unit region of the substrate portion 2.
Regions where the pair of electrodes 41 and 42 are provided and a
region between those regions define a unit region.
Each of the multiple heat generation portions 5 is embedded in the
substrate portion 2. The heat generation portions 5 are disposed
between the front surface layer 21 and the back surface layer 22.
Therefore, the heat generation portions 5 are not exposed to the
surface of the substrate portion 2. The heat generation portions 5
are protected by the substrate portion 2. The heat generation
portions 5 are disposed between the pair of electrodes 41 and 42.
The heat generation portions 5 extend linearly between the pair of
electrodes 41 and 42. The heat generation portions 5 can be
referred to as linear heat generation elements. The heat generation
portions 5 extend straight between the pair of electrodes 41 and 42
in a straight line. One end of the heat generation portions 5 is
electrically and mechanically connected to one electrode 41. The
other end of the heat generation portions 5 is electrically and
mechanically connected to the other electrode 42.
The heat generation portions 5 are each formed in a thin
plate-shape parallel to the surface of the substrate portion 2. The
heat generation portions 5 are capable of radiating the radiant
heat R by a heat supplied by energization. The heat generation
portions 5 can radiate the radiant heat R that causes the occupant
12, that is, a person to feel warmth by being heated to a
predetermined radiation temperature Tr. The volume of the heat
generation portions 5 is set so as to reach a temperature at which
the heat generation portions 5 can radiate the radiant heat R by
the heat supplied from the heat generation portions 5. The volume
of the heat generation portions 5 is set so that the temperature of
the electrodes 3 rises rapidly by the heat supplied from the heat
generation portions 5. The volume of the heat generation portions 5
is set small so as to cause a rapid temperature drop by radiating
the heat to an object coming in contact with the surface of the
radiant heater device 1. A thickness of the heat generation
portions 5 is set to be thin in order to maximize an area parallel
to the surface and minimize the volume. An area of the heat
generation portions 5 is set to a width suitable for radiating the
radiant heat R. The area of the heat generation portions 5 is set
to be smaller than that of the object, for example, a part of the
occupant 12, which is positioned facing the surface of the radiant
heater device 1.
The multiple heat generation portions 5 are disposed in parallel
with each other. The multiple heat generation portions 5 are
electrically connected in parallel to each other between the pair
of electrodes 41 and 42. The multiple heat generation portions 5
are disposed so as to define gaps 6 between the heat generation
portions 5.
The multiple heat generation portions 5 are disposed so as to be
substantially uniformly dispersed on the surface of the substrate
portion 2. The multiple heat generation portions 5 are disposed so
as to be distributed with a substantially uniform density in a
region between the pair of electrodes 41 and 42. The multiple heat
generation portions 5 are disposed in a distributed manner in most
areas of the unit region of the substrate portion 2.
The shapes and dimensions defining cross-sectional areas of the
electrodes 3 and 4 in an energization direction, as well as the
materials of the electrodes 3 and 4 are selected and set to provide
a low electrical resistance value. The cross-sectional areas and
materials of the electrodes 3 and 4 are set so as to provide an
excellent electrical conductor in order to distribute the current
evenly to the multiple heat generation portions 5. The shape and
dimensions defining a cross-sectional area of the heat generation
portions 5 along the energization direction, and the material of
the heat generation portions 5 are selected and set to provide a
high electrical resistance value so as to generate the radiant heat
R by energization. The material of the electrodes 3 and 4 and the
material of the heat generation portions 5 are different from each
other. The resistivity of the material of the electrodes 3 and 4 is
sufficiently lower than the electrical resistivity of the material
of the heat generation portions 5.
The electrodes 4 are elongated and have a longitudinal direction
along the axis Y. The electrodes 4 have a length EL along the axis
Y. The length EL corresponds to an energization direction in the
electrodes 4. The electrodes 4 have a width EW along the axis X.
The width EW is orthogonal to the energization direction. The
electrodes 4 have a thickness ET along the axis Z. The thickness ET
is less than the length EL and the width EW. Thus, the electrodes 4
provide a ribbon-shaped electrical conductor.
The heat generation portions 5 are elongated and have a
longitudinal direction along the axis X. The heat generation
portions 5 have a length HL along the axis X. The length HL
corresponds to the energization direction in the heat generation
portions 5. The heat generation portions 5 have a width HW along
the axis Y. The width HW is orthogonal to the energization
direction. The heat generation portions 5 have a thickness HT along
the axis Z. The thickness HT is less than the length HL and the
width HW. Thus, the heat generation portions 5 provide a
ribbon-shaped heat generation element.
The thickness HT is desirably set to be smaller than the width HW
(that is, HW>HT). The thickness HT is desirably set to be
smaller than 1 mm. The thickness HT is desirably set to be smaller
than 100 .mu.m.
The width EW is set to be larger than the width HW in order to
reduce the electric resistance value in the electrodes 4. In the
present embodiment, a cross-sectional area of the electrodes 4
orthogonal to the conduction direction is larger than the
cross-sectional area of the heat generation portions 5 orthogonal
to the energization direction. The resistivity of the electrodes 4,
which is smaller than the resistivity of the heat generation
portions 5, makes it possible to reduce the cross-sectional area of
the electrodes 4. For the same purposes, the thickness ET may be
set to be larger than the thickness HT.
The gaps 6 have a width GW. A length of the gaps 6 is the same as
the length HL of the heat generation portions 5. The multiple heat
generation portions 5 and the multiple gaps 6 are alternately
disposed over the overall length EL of the electrodes 4. The width
GW of the gaps 6 can be set to be equal to the width HW of the heat
generation portions 5. As a result, the multiple heat generation
portions 5 are uniformly dispersed and disposed. In addition, the
heat generation portions 5 and the gaps 6 having the fine widths HW
and GW, respectively, are disposed at high density. As a result, a
temperature distribution on the surface of the radiant heater
device 1 is restricted. Such a high-density arrangement of the fine
heat generation portions 5 contributes to radiating the uniform
radiant heat R from the surface of the radiant heater device 1.
According to the present embodiment, the radiant heater device 1 is
formed in a thin plate-shape. Further, the electrodes 3 and 4 and
the heat generation portions 5 buried inside the substrate portion
2 are in a film shape extending in parallel with the surface of the
substrate portion 2. The film-shaped electrodes 3 and 4 and the
film-shaped heat generation portions 5 are advantageous for
radiating the radiant heat R over a large area.
The heat generation portions 5 are made of a material that
generates the heat by energization. The heat generation portions 5
exhibit an electrical resistance value along the energization
direction so as to generate the heat by energization. The heat
generation portions 5 can be made of a metallic material. The heat
generation portions 5 can be made of a tin alloy. The heat
generation portions 5 can be made of an alloy containing copper,
silver, and tin. The heat generation portions 5 can also be made of
a heating wire material such as a stainless steel alloy, a
nickel-chromium alloy, or an aluminum alloy.
The electrodes 3 and 4 are made of a material having an electrical
resistivity lower than that of the material of the heat generation
portions 5. The electrodes 3 and 4 are made of a material that
generates less heat than the heat generation portions 5 when
energized. The electrodes 3 and 4 are made of a material having a
low resistivity so that a current can be evenly distributed to the
multiple heat generation portions 5. The electrodes 3 and 4 can be
made of a metallic material. The electrodes 3 and 4 can be made of
a tin alloy. The electrodes 3 and 4 can be made of an alloy
containing copper, silver or tin. The electrodes 3 and 4 can also
be made of an excellent conductor material such as a copper alloy
or an aluminum alloy.
When a predetermined voltage, for example, 12 V DC power is
supplied to the electrodes 31 and 32, the multiple heat generation
portions 5 generate the heat by a current flowing through the
multiple heat generation portions 5. The radiant heat R is provided
from the surface of the radiant heater device 1 by the multiple
heat generation portions 5 generating the heat. The temperature of
the multiple heat generation portions 5 rises earlier than the
temperature rise of the air in the interior by the heating device.
As a result, warmth can be imparted to the occupant 12 by the
radiant heat R earlier than the heating effect by the heating
device.
The volumes of the electrodes 4 and the heat generation portions 5
are set so as to reduce the heat capacity. The heat capacity of the
heat generation portions 5 is set so that when an object comes into
contact with the surface of the radiant heater device 1, the
surface temperature of the radiant heater device 1 at the contact
portion falls below a predetermined temperature in a short time. In
a desirable mode, the heat capacity of the heat generation portions
5 is set so that the surface temperature of the contact portion is
lower than 60.degree. C. when a human finger comes into contact
with the surface of the radiant heater device 1.
As described above, the multiple heat generation portions 5 are
disposed in parallel with each other inside the substrate portion 2
having a lower thermal conductivity than that of the heat
generation portions 5. Thus, the high heat conduction portions and
the low heat conduction portions are alternately disposed inside
the substrate portion 2. As described above, the heat generation
portions 5 according to the present embodiment has a structure in
which the heat transfer in the surface direction of the substrate
portion 2 is restricted.
The radiant heater device 1 according to the present embodiment
further restricts the heat transfer in the surface direction of the
surface member 80 by the surface member 80 provided on the front
surface layer 21 of the substrate portion 2.
The surface member 80 is made of fiber fabrics 81 and 82. In the
fiber fabrics 81 and 82, the space portion 80a recessed toward the
substrate portion 2 side in the thickness direction of the surface
member 80 is provided, and the space portion 80a restricts the heat
transfer in the surface direction of the surface member 80.
The fiber fabrics 81 and 82 according to the present embodiment are
configured of knitted fabrics formed by knitting multiple fibers
with air interposed between the fibers. The fiber fabric 81 has a
base fabric portion 810, and the fiber fabric 82 has a mesh portion
821. Although the base fabric portion 810 and the mesh portion 821
are schematically shown in FIG. 3, the knitted fabric is actually
configured as a three-dimensionally cubic knitted fabric. As shown
in FIG. 4A, the fiber fabrics 81 and 82 are at least partially
mesh-shaped. The mesh has a lattice shape. In other words, the
fiber fabrics 81 and 82 have uneven shapes formed on the surfaces
of the fiber fabrics 81 and 82.
The base fabric portion 810 is in the form of a thin sheet. The
mesh portion 821 has a knitted structure in which yarn members are
knitted to increase the density. The fiber fabrics 81 and 82
according to the present embodiment are formed inexpensively by
integrally knitting two knitted fabrics. The fiber fabrics 81 and
82 have a double mesh structure in which two knitted fabrics are
put on and knitted with each other.
The fiber fabrics 81 and 82 can be configured by chemical fibers
such as PET (that is, polyethylene terephthalate), PA (that is,
nylon), PPS (that is, polyphenylene sulfide), and natural fibers
such as silk. The present inventors have found that the thermal
conductivity of the knitted fabric according to the present
disclosure using those chemical fibers and natural fibers such as
silk is remarkably small as compared with the thermal conductivity
of the thermoplastic resin configuring the substrate portion 2, as
will be described below. FIG. 4B shows a schematic cross-sectional
view of a knitted fabric according to the comparative example, and
FIG. 4C shows a schematic cross-sectional view of the fiber fabrics
81 and 82 according to the present disclosure. As shown in FIGS. 4B
and 4C, the way of heat transfer is different between the
comparative example and the present disclosure. In the comparative
example, as shown in FIG. 4B, the resin material of the substrate
portion 2X is formed in a sheet shape or an uneven shape with a
substantially uniform density. As shown by arrows, the heat
conduction is uniformly performed through the resin disposed with a
substantially uniform density. On the other hand, as shown in FIG.
4C, in the base fabric portion 810 and the mesh portion 821 in the
present disclosure, multiple fibers are knitted with each other,
and are formed in a cross section of the fibers with air interposed
between the fibers. As a result, as shown by the arrows, a heat is
transferred mainly through fiber portions 80c rather than through
air portions 80a between the plurality of fibers. Therefore, a path
through which the heat is transferred is smaller than that of the
uniform resin material of the comparative example, and the heat
conduction is remarkably reduced.
Assuming that a contact area when the object comes in contact with
the surface member 80 is A, the thermal conductivity of the surface
member 80 is .lamda., and a distance by which the heat transfers is
L, the thermal resistance R when the object comes in contact with
the surface member 80 is expressed by the following Expression 1.
R=L/.lamda.A (Expression 1)
When a thickness of the surface member 80 is reduced by providing
the space portion 80a recessed in the thickness direction, the
distance L over which heat transfers is restricted, and therefore
the thermal resistance R is reduced. Therefore, the heat in the
thickness direction of the portion that comes in contact with the
object is easily transferred. However, in the radiant heater device
1, the heat generation portions 5 has a structure in which the heat
transfer in the surface direction of the substrate portion 2 is
restricted. Further, in the radiant heater device 1, a contact area
A with the object is restricted by the space portion 80a of the
surface member 80, and therefore the thermal resistance R is
increased, as compared with the case where the space portion 80a is
not provided in the surface member 80. Therefore, according to the
heater structure of the heat generation portions 5 and the
structure of the surface member 80 in the radiant heater device 1,
even if the temperature of the contact portion is high, the heat
transfer occurs quickly from the heat generation portions 5 in the
thickness direction of the surface member 80 at the moment of
contact, and thereafter, the heat transfer in the planar direction
of the heater and the surface member 80 is restricted. Therefore,
the temperature of the contact portion can be quickly lowered.
Also, the thermal discomfort to the occupant can be reduced.
A sum total thickness of the base fabric portion 810 and the mesh
portion 821 is preferably set to 1 mm or less. In order to reduce
the thermal resistance R, the sum total thickness of the base
fabric portion 810 and the mesh portion 821 is preferably set to
about 0.6 to 0.8 mm. A distance between the mesh portions 821
facing each other across the space portion 80a is preferably set to
about 1 mm to 3 mm. The thickness of the mesh portion 821 is
preferably set to about 0.3 mm.
In the verification by the present inventors, a surface temperature
of protrusion portions of the surface member 80 is set to about
105.degree. C., a temperature of the heat generation portions 5 at
that time is set to 125 to 130.degree. C., and a calculated value
of the surface temperature of recess portions of the surface member
80 is set to 115.degree. C. At that time, in the radiant heater
device 1, the surface temperature of the protrusion portions of the
surface member 80 at the moment when the object comes in contact
with the surface member 80 is about 41 to 42.degree. C., which is
reduced by about 1.degree. C. compared to other flat knitted
fabrics having the same thickness, and the effect of reducing the
temperature by about 3.degree. C. can be confirmed as compared with
the case where the knitted fabric is subjected to raising or
flocking. In addition, since the temperature of the recess portions
can be increased, it can be confirmed by evaluation that the
emissivity is increased by about 30% as compared with other flat
knitted fabrics having the same thickness.
According to the configuration described above, the surface member
80 is configured by the fiber fabrics 81 and 82 in which the space
portion 80a recessed toward the substrate portion 2 in the
thickness direction of the surface member 80 is provided and the
space portion 80a restricts the heat transfer in the surface
direction of the surface member 80. Therefore, the temperature of
the contact portion when the object comes into contact with the
contact portion can be lowered more quickly.
In addition, since the heat generation portions 5 are structured to
restrict the transfer of heat in the surface direction of the
substrate portion, the temperature of the contact portion when an
object comes into contact with the contact portion can be more
quickly lowered.
FIG. 5 shows the evaluation result of the contact temperature of
the finger to the radiant heater device 1 according to the
difference in the unit weight (for example, the thickness and the
weight) of the surface member 80. A horizontal axis represents the
thickness and weight of the surface member 80, and a vertical axis
represents a temperature of the contact portion. Assuming that the
temperature at which pain due to general heat is felt (that is,
43.degree. C.) is Ts, if the temperature of the surface member 80
is lower than the temperature Ts, it can be determined that the
lower temperature is safe even if the finger or the like comes into
contact with the surface member 80. In the flat knitted fabric in
which the space portion 80a is not provided, as the thickness is
smaller, the thermal resistance in the thickness direction becomes
smaller, so that the heat transfer to the finger becomes large and
the contact temperature becomes slightly high. Further, as the
thickness is larger, the heat capacity of the surface member is
greater, and therefore the heat transfer from around the contact
portion becomes larger and the contact temperature becomes higher.
From the above result, it has been found that the temperature of
the contact portion tends to be convex downward with respect to the
thickness and weight of the surface member 80. The optimum value is
0.6 to 0.8 mm in thickness.
FIG. 6 shows the evaluation result of the contact temperature of
the finger with the radiant heater device 1 when the knitted fabric
is raised or flocked. It has been found that when the knitted
fabrics are raised or flocked, the temperature of the contact
portion at the time of contact tends to rise more than when the
knitted fabrics are not raised or flocked. In addition, it has been
found that the degree of temperature rise of the contact portion at
the time of contact tends to increase as a proportion of raised
fabric is increased. Further, even when short fibers are
transplanted on the heater surface with the use of an adhesive, a
further increase in temperature can be confirmed. it can be
estimated that this is because the contact area of the surface
member with the finger increases and the thermal resistance
decreases. In other words, it has been found that it is better not
to subjecting the knitted fabrics to raising or flocking in order
to lower the temperature of the contact portion.
FIG. 7 shows the evaluation result of the contact temperature of
the finger to the radiant heater device 1 according to the
difference in the composition of the surface member. In a joint
skin (i.e., synthetic leather) whose surface is covered with
acrylic or PVC (i.e., vinyl chloride) or the like, the thermal
conductivity of the surface is increased, and thus the heat
transfer is increased, so that the temperature of the contact
portion at the time of contact is increased. It can be presumed
that the nonwoven fabric made of only short fibers has a contact
temperature equivalent to that of the knitted fabric, and small air
chambers in the nonwoven fabric serve as heat insulation in the
planar direction, thereby reducing the heat transfer.
FIG. 8 shows the evaluation result of the contact temperature of
the finger to the radiant heater device 1 according to the
difference in the amount of unevenness of the knitted fabric of the
surface member. As with the above description, the typical thermal
pain temperature (that is, 43.degree. C.), is denoted by Ts, a
temperature falling below the typical thermal pain temperature can
be considered safe. It has been clearly found that as the
unevenness due to the mesh is larger, the contact temperature of
the contact portion is lower. When the unevenness is about 0.3 mm
or lower, the temperature is reduced by the amount equal to that of
the knitted fabric, but when the amount of unevenness exceeds 0.3
mm, the contact area at the time of contact is reduced and the
contact temperature is greatly reduced. In the above evaluation,
the above effect can be confirmed in a sample in which when the
thickness of the protrusion portion is 0.9 to 1.0 mm, the
difference in the recess and the protrusion is set to 0.5 to 0.7
mm.
FIG. 9 shows the evaluation result of the contact temperature to
the finger of the radiant heater device 1 due to the difference in
the amount of unevenness in the surface shape using the nonwoven
fabric. In the flat portion in which the surface of the nonwoven
fabric is made dense by press, the thermal conductivity becomes
remarkably large, and the contact temperature increases extremely.
In addition, even in the shape of a leather grain type or a fabric
pattern having little unevenness, there is a tendency that the
contact temperature lowers little. In that case, the amount of
unevenness is about 0.1 to 0.2 mm. On the other hand, it can be
confirmed that the contact temperature is lowered by increasing the
amount of unevenness of the groove portion due to a stripe pattern,
and, in that case, the advantage can be confirmed when the amount
of unevenness is about 0.3 mm or more.
FIG. 10 shows the evaluation result of the amount of radiation of
the radiant heater device 1 according to the difference in the
amount of unevenness of the surface member. In that evaluation, the
amount of radiation at the surface temperature (for example, about
100.degree. C.) is measured, and the magnitude of the amount of
radiation is compared with that of a flat knitted fabric as a
reference. According to the above result, it can be confirmed that
when the unevenness of the mesh is small, the radiation amount is
almost the same as that of the knitted fabric, but the radiation
amount is increased more as the unevenness of the mesh is larger,
and is increased by about 30%.
Second Embodiment
A radiant heater device 1 according to a second embodiment of the
present disclosure will be described with reference to FIGS. 11 to
12. The fiber fabrics 81 and 82 according to the first embodiment
are composed of knitted fabrics, but a fiber fabric of the present
embodiment is formed of a nonwoven fabric 83. A nonwoven fabric 83
is formed in a fabric shape in which multiple fibers are
intertwined without being knitted, and a heat conduction is reduced
by interposing air between the multiple fibers. Also in the present
embodiment, the heat conduction is reduced in the same manner as
shown in FIG. 4C. On a surface of the fiber fabric 83 according to
the present embodiment, press portions 83a each serving as a linear
recess portion and base fabric portions 83b each serving as a
linear protrusion portion are alternately formed. The press
portions 83a are recessed toward a front surface layer 21 side of
the substrate portion 2. The press portions 83a and the base fabric
portions 83b are formed by pressing the nonwoven fabric 83 with the
use of a mold in which linear protrusion portions are provided. As
described above, the press portions 83a and the base fabric
portions 83b are inexpensively formed by press processing.
A thickness of the press portions 83a is thinner than that of the
base fabric portions 83b. A density of fibers in the press portions
83a is higher than a density of fibers in the base fabric portions
83b. As a result, a thermal resistance of the press portions 83a in
a thickness direction is smaller than that of the base fabric
portions 83b.
In the present embodiment, the same advantages as those obtained
from the configuration common to the first embodiment can be
obtained in the same manner as in the first embodiment.
In verification by the present inventors, the surface temperature
of the protrusion portion of the surface member 80 is set to about
105.degree. C., the temperature of the heater heat generation
portion at that time is set to 125 to 130.degree. C., and a
calculated value of the surface temperature of the recess portion
of the surface member 80 is set to 115.degree. C. At that time, in
the radiant heater device 1 according to the present embodiment,
the surface member temperature at the moment when the object comes
in contact with the surface member 80 is about 42.degree. C., and
the effect of reducing the surface member temperature by about
2.degree. C. as compared with other flat nonwoven fabrics having
the same thickness, and the effect of reducing the temperature by
about 3 to 4.degree. C. as compared with fabrics subjected to a
grain process in which the unevenness difference is as small as
about 0.2 mm can be confirmed.
Third Embodiment
A radiant heater device 1 according to a third embodiment of the
present disclosure will be described with reference to FIG. 13.
The fiber fabrics 81 and 82 according to the first embodiment have
the mesh shape, but fiber fabrics 81 and 82 according to the
present embodiment have a honeycomb shape. In this manner, the
fiber fabrics 81 and 82 may have a honeycomb shape.
In the present embodiment, the same advantages as those obtained
from the configuration common to the first embodiment can be
obtained in the same manner as in the first embodiment.
OTHER EMBODIMENTS
(1) In each of the embodiments described above, the multiple heat
generation portions 5 are disposed in parallel with each other
inside a substrate portion 2 having a lower thermal conductivity
than the heat generation portions 5, and the heat generation
portions 5 have a structure to restrict a heat transfer in a
surface direction of the substrate portion 2. On the other hand,
for example, the heat generation portions 5 may be formed to have a
planar shape without a structure to restrict the heat transfer in
the surface direction of the substrate portion 2.
(2) In the second embodiment, the press portions 83a having a
linear shape are formed on the nonwoven fabric 83, but a shape
other than a linear shape, such as a lattice shape or a honeycomb
shape, may be used. Through holes penetrating both surfaces of the
nonwoven fabric 83 may be provided in the nonwoven fabric 83, and a
space defined by the through-holes may be the space portion
80a.
(3) The fiber fabric according to the first embodiment has the
double mesh structure in which two fiber fabrics are put on each
other, but may have a mesh structure in which one fiber fabric is
subjected to mesh processing.
It should be noted that the present disclosure is not limited to
the above-described embodiments, and can be change as appropriate.
The embodiments described above are not independent of each other,
and can be appropriately combined except when the combination is
obviously impossible. In each of the embodiments described above,
it is needless to say that the elements constituting the embodiment
are not necessarily indispensable except when it is clearly
indicated that they are particularly indispensable, when they are
clearly considered to be indispensable in principle, and the like.
Further, in each of the embodiments described above, when numerical
values such as the number, numerical value, quantity, range, and
the like of the constituent elements of the embodiment are referred
to, except in the case where the numerical values are expressly
indispensable in particular, the case where the numerical values
are obviously limited to a specific number in principle, and the
like, the present disclosure is not limited to the specific number.
Further, in each of the embodiments described above, when referring
to the material, shape, positional relationship, and the like of
the components and the like, except in the case where the
components are specifically specified, and in the case where the
components are fundamentally limited to a specific material, shape,
positional relationship, and the like, the components are not
limited to the material, shape, positional relationship, and the
like.
CONCLUSION
According to a first aspect shown in part or all of the embodiments
described above, the radiant heater device for generating a radiant
heat includes a plate-shaped substrate portion made of an
electrically insulating material, a sheet-shaped surface member
disposed on one surface side of the substrate portion, and a heat
generation portion formed on the other surface side of the
substrate portion. The surface member is formed of a fiber fabric
in which the space portion recessed toward the substrate portion in
the thickness direction of the surface member is provided and the
heat transfer in the surface direction of the surface member is
restricted by the space portion.
According to a second aspect, the fiber fabric is configured by
interposing air between multiple fibers. According to a third
aspect, the heat generation portion has a structure in which the
heat transfer in the surface direction of the substrate portion is
reduced. Therefore, the temperature of the contact portion when the
object comes into contact with the contact portion can be quickly
lowered.
According to a fourth aspect, the fiber fabric has the mesh shape.
In this manner, the fiber fabric can have the mesh shape.
According to a fifth aspect, the fiber fabric has the double mesh
structure in which two knitted fabrics are put on each other.
Therefore, the thickness can be made larger than that in the case
of using the single fiber fabric, and the surface member having the
optimum thickness can be formed.
According to a sixth aspect, the mesh shape is the lattice shape.
In this manner, the mesh shape can be the lattice shape.
According to a seventh aspect, the mesh shape is the honeycomb
shape. In this manner, the mesh shape may be the honeycomb
shape.
According to an eighth aspect, the fiber fabric is formed of the
knitted fabric. Therefore, a sense of luxury can be also
provided.
According to a ninth aspect, the fiber fabric is formed of the
nonwoven fabric. Therefore, a cushioning action can be exerted when
the object such as the finger comes into contact with the surface
member.
* * * * *